It is well known in the art of food processing to dehydrate food materials, e.g. vegetables, to prevent decay and/or to reduce weight. Prior to consumption such dehydrated materials are to be reconstituted with water so as to restore the appearance and eating qualities (flavour, texture etc.) of the original (fresh) food material.
Prior art endeavors in this field have resorted to rather severe dehydration treatments (e.g. hot air drying) of the fresh product and/or to complex treatments of the product (e.g. freeze drying) and in some instances to the use of chemical treatments. The adverse impact of such processes on a number of characteristics of the fresh starting material is well known. For instance, hot air drying will usually have a significant adverse effect on the flavour and the colour of the fresh starting material. Also, hot air dried products generally do not rehydrate well. Freeze drying typically yields dehydrated products that are superior to hot air dried products in terms of flavour and colour. However, freeze drying is known to cause rupture of cells and to increase the permeability of vegetables to water. Furthermore, freeze drying is not particularly economical as it is a very slow process that consumes a lot of energy.
In short, the prior art has long recognised a need for a simple, effective method for preserving the fresh characteristics of pieces of intact plant or animal tissue. In addition there is a general need for an economical dehydration method that does not adversely affect the desirable characteristics of the starting material as a result of e.g. heat induced or oxidative damage.